Method for evacuating packages

ABSTRACT

A filled flexible receptacle such as a thermoplastic bag containing a food product is evacuated by placing the filled portion of the bag in a first vacuum chamber; extending the neck of the bag into a second and adjacent chamber; evacuating the first chamber thereby causing the bag to balloon outwardly away from the product; and, while the first chamber is being evacuated, evacuating the second chamber and, consequently, evacuating the interior of the ballooned bag; thereafter, when evacuation of the bag is complete, elevating the pressure in the first chamber to collapse the bag firmly around the product and immediately closing the bag thereby making an evacuated package.

United States Patent Burrell *Dec. 30, 1974 METHOD FOR EVACUATINGPACKAGES Prima Examiner-Travis S. McGehee 75 Inventor: W11 m E. B 11 os. W 1 I la uncan C Attorney, Agent, or Firm-John J. Toney; William D.[73] Assignee: W. R. Grace & C0., Duncan, SC. L e, Jr; Richard G.Jackson Notice: The portion of the term of this patent subsequent toSept. 3, 1991, has been disclaimed.

Filed: June 19, 1974 Appl. No.: 480,907

[5 7] ABSTRACT A filled flexible receptacle such as a thermoplastic bagcontaining a food product is evacuated by placing the filled portion ofthe bag in a first vacuum chamber; extending the neck of the bag into asecond and adjacent chamber; evacuating the first chamber therebycausing the bag to balloon outwardly away from the product; and, whilethe first chamber is being evacuated, evacuating the second chamber and,consequently,

[52] U.S. Cl 53/22 B; 53/112 B 51 1m. (:1. B65B 31 02 evachahhg the thehahmhed hag; 58 Field of Search 53/22 B 86 112B when evachahoh of thebag is cmhplete elevating the pressure in the first chamber to collapsethe bag [56] References Cited firmly around the product and immediatelyclosing the UNITED STATES PATENTS bag thereby making an evacuatedpackage.

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N i IIII!IIIII FIG. 7

FIG. 8

This is a continuation of application Ser. No. 375,300 filed June 29,1973.

FIELD OF THE INVENTION This invention relates to a method and apparatusfor evacuating receptacles, especially impervious, flexible receptaclessuch as thermoplastic bags and pouches. The invention has particularapplication in the vacuum packaging of fresh and frozen food productssuch as beef, poultry, ham, cheese, etc.

BACKGROUND OF THE INVENTION A number of methods are available in theprior art for packaging food products such as meat and poultry inflexible containers such as thermoplastic packages and bags. In someprocesses the product is placed in a bag, a vacuumizing nozzle is theninserted into the bag, the mouth of the bag is gathered around thenozzle while the vacuum acting through the nozzle withdraws the air fromthe bag, and after evacuation is completed the bag is either clampedshut with a metal clip or heated welded shut. In this method completeevacuation of the bag is difficult to obtain because the meat product isusually damp and tends to cling to the bag wall so that surface crevicesin the meat will form a pocket with the bag wall which blocks thepassage of air out of the bag during the vacuumizing process.Accordingly, it is one object of the present invention to provide amethod and apparatus for satisfactorily evacuating bags filled with meatproducts and the like.

Rather than insert a nozzle into a filled, impervious pouch or bag,other prior art methods employ a vacuum chamber into which a filled bagis placed in open condition. Subsequent evacuation of the chamber alsoevacuates the bag; and, before the chamber is opened, the bag is sealedor closed within the chamber. An apparatus for carrying out such aprocess is disclosed in US. Pat. No. 2,790,284 issued on Apr. 30, 1957to P. B. Hultkrans. However, the immediately foregoing method still doesnot solve the problem of evacuation of a bag filled with a crevicecontaining product such as meat or poultry. Accordingly, it is anotherobject of the present invention to provide a method and apparatuswhereby a package filled with a product which tends to cling to thepackage wall may be evacuated and closed within a vacuum chamber.

Another prior art method and apparatus for evacuating a filled bagwithin a vacuum chamber is disclosed in U.S. Pat. No. 3,714,754 issuedon Feb. 6, 1973 to Edward L. Holcombe et al. In the Holcombe et al.patent, the bag loaded with a product is placed in a vacuum chamber andthe neck of the bag is clamped over an extractor which can withdrawvacuum from the bag independently of the vacuum applied within thechamber. However, this method requires the manual locating of the bagneck around the extractor tube and the manual clamping of the bag neckthereto. Accordingly, it is another object of the present invention toprovide an independent means for evacuating a bag within a vacuumchamber which requires a minimum of manual handling and locating of thebag within the vacuum chamber.

The foregoing and other objects are achieved by the process andapparatus described below.

SUMMARY OF THE INVENTION In one aspect, the present invention is aprocess of evacuating filled receptacles such as thermoplastic bags,pouches, and the like by placing the filled portion of the bag in afirst vacuum chamber, extending the neck of the bag into a second andadjacent vacuum chamber, evacuating the first chamber thereby causingthe bag to balloon outwardly away from the product; and, while saidfirst chamber is being evacuated, evacuating the second chamber and,consequently, evacuating the interior of the balloned bag; thereafterwhen evacuation of the bag is complete, elevating the pressure in thefirst chamber to collapse the bag firmly around the product andimmediately closing the bag thereby making an evacuated package.

In another aspect, the present invention is a process of evacuating andclosing flexible, impervious receptacles such as pouches, bags, and thelike which have at least one opening and contain at least one product,the process comprising the steps of confining the product containing aportion of the receptacle within a first region, confining a portion ofthe receptacle which contains the opening in a second region so that theinterior of said receptacle is in communication with the second regionthrough said opening of the receptacle, reducing the pressure withinsaid first region and, subsequently, reducing the pressure within saidsecond region so that the interior of the receptacle is evacuated,elevating the pressure in the first region, and, thereafter, closing theopening to make an evacuated package.

In still another aspect, the present invention is an apparatus forevacuating and closing flexible, impervious receptacles such as pouches,bags, and the like which have at least one opening and contain at leastone product and the apparatus comprises a first vacuum chamber with asecond vacuum chamber adjacent to it and an aperture connecting the twochambers for passing the portion of the receptacle containing an openingtherethrough. Means to evacuate the first and second chambers and meansto close the package when its evacuation is completed are included inthe apparatus. Also, the closing means for the apparatus may be either aclip applying device or a heat seal apparatus located within one of thevacuum chambers.

The invention may be better understood by reference to the drawingsdescribed below and the following Description of the PreferredEmbodiment.

DESCRIPTION OF THE DRAWINGS In the drawings which are appended heretoand made a part of this disclosure;

FIG. 1 is a side elevational representation of a preferred apparatusaccording to the present invention in which the vacuum chambers of theapparatus are closed and a chamber wall is removed to show the interiorarrangement;

FIG. 2 is a top plan view of the apparatus shown in FIG. 1 with both ofsaid vacuum chambers open;

FIG. 3 is an isometric representation of a section of the lower portionof both of said vacuum chambers showing a filled package ready to beevacuated;

FIG. 4 is a representation in partial section showing the gathering armsof the preferred closing means of the preferred apparatus;

FIG. shows in partial section a clip being applied to a bag neck whichhas been gathered by the gathering arms shown in FIG. 4;

FIG. 6 shows the clip of FIG. 5 being closed around the gathered bagneck as the clip is forced into the clip anvil;

FIG. 7 is a sectional schematic side representation of the base of thevacuum chambers of the preferred embodiment showing the clip magazineand the clip punch and driving wheel; and,

FIG. 8 is a front elevational representation of the drive and timingwheel shown in FIG. 7.

DEFINITIONS As used herein, the terms listed below will be understood tohave the meaning set forth beside each term:

Receptacle means any container for receiving an article or product to bepackaged in the receptacle and includes bags and pouches.

Bag means a receptacle or container constructed from tubular stock bysealing one end of the tube. A bag may be pleated or gusseted.

Pouch means a receptacle or container constructed from sheet stock. Asingle or multiple sheets may be used; and, commonly a pouch may be madeby folding a single sheet and sealing the free edges of the sheettogether.

Aperture means a hole in a wall that may be of any shape and includesslot, oval, circular, rectangular, and irregular shaped holes. Anaperture may be formed by joining two wall sections that haveindentations in one or both of the surfaces so joined.

Vacuum means a pressure level lower than atmospheric pressure and may beexpressed in lbs./sq.in. or in inches of Hg. A high vacuum means a verylow pressure level.

I-Ieat shrinkable" means that the particular material referred to willshrink upon the application of heat.

Heat sealable means that the particular material referred to can bewelded to itself under the influence of temperature and pressure.

Opening" in a receptacle means a passageway from the exterior of thereceptacle to the interior; and, in the case of a bag, the opening canbe the bags mouth and the part of the bag containing the opening wouldbe the bags neck.

PREFERRED EMBODIMENT In FIG. 1, a double chamber vacuumizing apparatus 1is shown in a side elevational representation with the side wall of theapparatus cut away so that the interior arrangement may be clearly seen.Also, reference will be made to FIG. 2 which is a top plan view of theapparatus of FIG. 1 with the hinged cover or head 3 being open. Thecover 3 is hinged to base member 2 which is divided by lower chamberdivider wall 12 which cooperates with the upper divider wall 11 toseparate apparatus 1 into the two chambers or regions 4 and 5. The firstand larger region or chamber 4 is the product chamber in which theportion of a bag or receptacle 9 containing a product 8 is placed onproduct conveyor 14. The receptacle opening or bag neck is extended intothe second and smaller region 5 which serves as the receptacle or bagevacuation chamber. The second chamber 5 is evacuated through vacuumport 7 and the first chamber 4 is evacuated through vacuum port 6.

Looking now at FIG. 3, the extension of the neck of bag 9 from the firstchamber 4 into the second chamber 5 can be more clearly seen. Theoperator of the apparatus 1 receives the bag 9 filled with a product 8and places the bag on the conveyor 14 and brings the neck of the bagdown through the bag neck guide 13 and extends the neck of the bagacross walls 18a and 18b of the gathering arm track 18, across plungerhousing 21, cutter housing 22, and the recess 12a in wall 12 so that theopening 9b of the package is located in the second region or chamber 5just above the evacuation port 7. The recess 12a in the wall 12 formsthe lower half of the aperture in the wall which divides chambers 4 and5 and this aperture and wall is completed when the cover 3 is rotatedinto the position shown in FIG. 1 so that a corresponding recess in wall11 forms the upper half of the divider wall aperture.

Once the chamber is closed evacuation of chamber 4 begins through vacuumport 6. Any conventional vacuum pump which is well known in the art maybe used and be connected to vacuum port 6 to evacuate chamber 4. Asvacuum is applied the chamber will be evacuated very rapidly, in theorder of two to three seconds to a low level of pressure or around 27inches of Hg. and further reduction in pressure takes a significantlylonger period of time. The bag neck sufficiently fills the aperturebetween chambers 4 and 5 so that very little air is leaked from thesecond region 5 into the first region 4 during this phase of evacuation.In this initial phase, the bag 9 will balloon outwardly as shown bydotted lines 10 because of the difference in pressure between theinterior of the bag 9 and the chamber 4. This outward expansion orbalooning of the bag also occurs in the bags neck region and theexpanded neck further seals the aperture between chambers 4 and 5. Whilethe bag is ballooned into shape 10, evacuation of the second region orchamber 5 is begun. This will usually be of the order of 5; sec. afterthe beginning of the evacuation of chamber 4. Chiefly because of itssmaller size, the evacuation of the second chamber 5 proceeds at a morerapid rate than that of first chamber 4 and overtakes the vacuum levelin first chamber 4 thus causing the ballooned bag 10 to begin tocollapse back onto product 8. The second chamber 5 will reach a vacuumlevel of 28 inches of Hg. or lower depending on the period of timevacuum is supplied through port 7. As the vacuum level in the secondchamber 5 is reduced below that in chamber 4 and the bag 9 begins tocollapse back upon the product 8, atmospheric pressure is restored inchamber 4 by stopping the vacuum pumping action through port 6 andventing the chamber to the atmosphere by valve means which are notshown. This sudden increase in the pressure differential between theinside and outside of the bag will cause the bag to collapse ratherrapidly and suddenly driving out any remaining air. Immediately as thistakes place, the bag is clipped and closed as will be described morefully hereinafter.

Once the bag is clipped and closed, the excess bag neck material istrimmed off and the head or cover 3 is opened and conveyor 14 will startup and deliver the sealed bag to conveyor 16 while the operator ispreparing to place another filled bag within apparatus 1 to begin theprocess again.

When, as described above, the bag balloons outwardly to the shape 10 thebag wall is separated from the product 8 and any crevices or cavities inthe product are exposed to the space which now exists between product 8and the expanded bag wall 10. Thus, when evacuation of the secondchamber 5 begins, a continuous passageway exists whereby a substantialportion of the surface of the product 8 is brought directly under theinfluence of the vacuum being drawn through second chamber 5.

A preferred package or bag closing and sealing means is illustrated inFIGS. 3 7., FIG. 4. is a view in partial section looking along thedirectionof lines 4-4 of FIG. 3. This view is from between walls 18a and18b of the lower gathering arm guide track 18 and between walls 17a and17b of the upper gathering arm track 17. In FIG. 4 bag neck 9a is shownpartially compressed between the bag neck guide 13 and walls 17a and18a. Gathering arms 25 move inwardly towards each other to furthercompress the bag neck 8 into the shape shown in FIG. 5. As the gatheringarms 25 have moved more closely together to wedge the bag neck 9a into asmaller space, plunger 24 drives clip 37 up around the gathered bag neck9a and forces the clip towards anvil 19. Further motion of the plungerforces the clip into the anvil l9 and bends it into the shape shown inFIG. 6 securely around the bag neck 19 thereby closing and sealing same.As this is completed cutter arm 26 with serrated cutter blade 27 isdriven upwardly to cut off the excess bag material which extends beyondclip 37. The clip 37 is taken from the group of clips 33 contained inclip magazine 32 shown in FIG. 7. The clips 33 are urged forward in themagazine 32 under the influence of clip spring 34 and are delivered toplunger 24 immediately below plunger housing 21. Plunger 24 is connectedto plunger crank arm 29 at pivot 30, and crank arm 29 is driven bytiming wheel 28 to which it is connected by crank pin 35.

Cutter arm 26 is driven upwardly through cutter housing 22 to sever theexcess bag neck material and the drive means for cutter arm 26 is notshown but may be a pneumatically operated cylinder or an electricallydriven solenoid, both of which drive means are well known in the art.

An alternate method and means for closing a package or bag afterevacuation is to remove the bag neck guide 13 shown in FIG. 3 and widenthe aperture opening 12a to correspond to the width of the flattened bagneck. The clip applying means may be eliminated in this alternateclosure means and a sealing bar may be substituted for the blade 27 withthe sealing bar being the same width as the aperture 12a. Bar 27 may beelectrically resistance heated and a pressure backing member may besubstituted for the cutter track 38 as shown in FIG. 6 so that when thearm 26 is driven upwardly after the evacuation of the bag the heated bar27 will contact the flattened bag neck 9a and press same against thepressure backing member 38. The bar would dwell sufficiently long in itsposition of pressing the bag neck against the backing member 38 untilthe bag is sealed to itself. Of course, for this alternate method andmeans to be employed the bag material must be of a type that will weldto itself under the influence of heat and the thermoplastic materialssuch as polyethylene, ethylene vinyl acetate copolymers, saran, and thelike with the appropriate coatings and surface treatments are suitablefor this purpose.

FIG. 8 is a frontal view of the plunger drive wheel 28 which is drivenby pinion 36 which, in turn, is driven by a conventional electricalmotor which is not shown. Crank pin 35 is connected to plunger crank 29and at the beginning of each cycle crank pin 35 is at bottom dead centerof the wheel. The time represented by t is the time from the beginningof the clips engagement with the anvil tothe end of the engagement asthe plunger withdraws. Referring also to FIG. 7, timing cams may beplaced on shaft 31 on which wheel 28 is mounted and these cams can beused to control such functions as the venting of the chambers toatmosphere as the clipping and cutting cycle is completed.

Referring now to FIGS. 1 81, a semi-automatic operation of the foregoingdescribed apparatus according to the process of the present inventionwill be described. In the following description valves, cams, a timer,vacuum pump, pressure sensor, etc. are mentioned. None of these areshown in the drawings and each is a conventional item whose use andapplication is familiar to those skilled in the packaging machineryarts. The packaging cycle begins when the operator manually places afilled bag into first chamber 4 and extends the neck into second'chamber5. The operator then closes the chambers with cover 3 and the closingactuates a microswitch which starts a timer and opens the valve to port6 so that a vacuum pump can evacuate chamber 4. At a predetermined time,preferably of the order of A or. of a second after the evacuation of thefirst chamber has begun depending on the size of the chamber and powerof the vacuum pump, the evacuation of the second chamber is started bythe timer opening the valve connecting port 7 with the vacuum pump.During this time ballooning of the bag; 9 to shape 10 will haveoccurred. When the pressure in the first chamber reaches a preset level,preferably about 26 or 27 in. I-Ig., a pressure sensor in' the firstchamber shuts off the vacuum in the first chamber and simultaneouslysends a signal through a delay timer to the electric drive motor forpinion 36. At this point, the timing and drive wheel 28 is at theposition shown in FIG. 8 with the crank pin at bottom dead center. Thetimed signal can be preset for any given duration and is preferablyabout 1% seconds which means that wheel 28 will start to make onecomplete revolution at the end of that preset period of time. Timingcams are located on the supporting shaft or axle 31 of wheel 28 and aswheel 28 rotates in a counterclockwise manner (FIG. 8) one of the camswill actuate a valve causing the first chamber to vent to atmosphereprior to reaching time span Venting the first chamber to atmospherecauses the bag 9 to collapse or, rather, be violently pushed against theproduct since the bag interior is at the pressure level of the secondchamber which now will have reached lower than 28 in. I-Ig. This violentcollapsing of the bag drives out any residual air in the bag immediatelybefore the gathering and clipping cycle begins with time span During tthe bag neck is gathered and the clipper plunger 24 drives clip v37 intoposition around the gathered bag to seal and close same. Followingwithdrawal of the plunger and trimming of the bag neck at the end of asecond cam shuts off the vacuum to the second chamber and vents thatchamber to the atmosphere. The cover 3 may now be raised and while theoperator is getting another filled bag ready, conveyor 14 moves thecompleted package to exit conveyor 16.

It is to be understood that the present invention is not limited to bagsand pouches but can be applied generally to any receptacle whose wallswill flex outwardly under the influence of a pressure differential andwill conform to a wall aperture. Furthermore, as set forth above, theshape of the wall aperture may be made to conform to the shape of thereceptacle opening and to the closing and sealing method desired.

One particularly desirable package results from the process andapparatus of this invention when a meat or poultry product is enclosedin a heat shrinkable, essentially gas impervious, thermoplastic bag.After the meat product has been sealed in the bag and the resultingpackage conveyed out of the apparatus, the package is passed througheither a hot water bath or through a hot air tunnel to shrink andfurther tighten the bag material around the product. The tight grip ofthe shrunken material protects the product from pinhole leakage becausethe material is so firmly pressed against the product that even when ahole or cut occurs the hole is essentially sealed by the adjacent orexposed portion of the product so that no air can enter the package.

I claim:

1. In the process of evacuating filled thermoplastic bags, pouches, andthe like, the improvement which comprises:

a. providing adjacent first and second vacuum chambers with an apertureconnecting said chambers;

b. placing the filled portion of the bag in the first vacuum chamber,

c. extending the neck of the bag into the second and adjacent vacuumchamber, said bag neck passing through said aperture whereby the mouthof said bag is unrestrained and open within the second chamber,

d. evacuating the first chamber; and, subsequently, 30

8 e. evacuating the second chamber at a more rapid rate than said firstchamber is evacuated, thereby evacuating said bag,

f. stopping the evacuation of the said chambers when the evacuation ofthe second is completed,

g. closing and sealing said bag; and,

h. removing said sealed bag from said first chamber.

2. The process of claim 1 wherein said sealed bag is removed from saidfirst chamber and delivered to a conveying means.

3. A process of evacuating and closing flexible, impervious receptaclessuch as pouches, bags and the like which have at least one opening andcontain at least one product comprising the steps of:

a. confining the product containing portion of said receptacle within afirst region;

b. confining a portion of the receptacle which contains said opening ina second region so that the interior of said receptacle is incommunication with said second region through said opening;

reducing the pressure within said first region thereby causing at leasta part of said receptacle to move outwadly away from contact with saidproduct; and, subsequently,

reducing the pressure within said second region to evacuate the interiorof said receptacle so that the receptacle again contacts the product;and, closing said opening thereby making an evacuated,

sealed, package.

1. In the process of evacuating filled thermoplastic bags, pouches, andthe like, the improvement which comprises: a. providing adjacent firstand second vacuum chambers with an aperture connecting said chambers; b.placing the filled portion of the bag in the first vacuum chamber, c.extending the neck of the bag into the second and adjacent vacuumchamber, said bag neck passing through said aperture whereby the mouthof said bag is unrestrained and open within the second chamber, d.evacuating the first chamber; and, subsequently, e. evacuating thesecond chamber at a more rapid rate than said first chamber isevacuated, thereby evacuating said bag, f. stopping the evacuation ofthe said chambers when the evacuation of the second is completed, g.closing and sealing said bag; and, h. removing said sealed bag from saidfirst chamber.
 2. The process of claim 1 wherein said sealed bag isremoved from said first chamber and delivered to a conveying means.
 3. Aprocess of evacuating and closing flexible, impervious receptacles suchas pouches, bags and the like which have at least one opening andcontain at least one product comprising the steps of: a. confining theproduct containing portion of said receptacle within a first region; b.confining a portion of the receptacle which contains said opening in asecond region so that the interior of said receptacle is incommunication witH said second region through said opening; c. reducingthe pressure within said first region thereby causing at least a part ofsaid receptacle to move outwadly away from contact with said product;and, subsequently, d. reducing the pressure within said second region toevacuate the interior of said receptacle so that the receptacle againcontacts the product; and, e. closing said opening thereby making anevacuated, sealed, package.